David 'Digit' Turner | 5d8f37a | 2009-09-14 14:32:27 -0700 | [diff] [blame] | 1 | /* |
| 2 | * QEMU BOOTP/DHCP server |
| 3 | * |
| 4 | * Copyright (c) 2004 Fabrice Bellard |
| 5 | * |
| 6 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 7 | * of this software and associated documentation files (the "Software"), to deal |
| 8 | * in the Software without restriction, including without limitation the rights |
| 9 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 10 | * copies of the Software, and to permit persons to whom the Software is |
| 11 | * furnished to do so, subject to the following conditions: |
| 12 | * |
| 13 | * The above copyright notice and this permission notice shall be included in |
| 14 | * all copies or substantial portions of the Software. |
| 15 | * |
| 16 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 17 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 18 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| 19 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 20 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 21 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 22 | * THE SOFTWARE. |
| 23 | */ |
| 24 | #include <slirp.h> |
| 25 | |
| 26 | /* XXX: only DHCP is supported */ |
| 27 | |
| 28 | #define NB_ADDR 16 |
| 29 | |
| 30 | #define START_ADDR 15 |
| 31 | |
| 32 | #define LEASE_TIME (24 * 3600) |
| 33 | |
| 34 | typedef struct { |
| 35 | uint8_t allocated; |
| 36 | uint8_t macaddr[6]; |
| 37 | } BOOTPClient; |
| 38 | |
| 39 | static BOOTPClient bootp_clients[NB_ADDR]; |
| 40 | |
| 41 | const char *bootp_filename; |
| 42 | |
| 43 | static const uint8_t rfc1533_cookie[] = { RFC1533_COOKIE }; |
| 44 | |
| 45 | #ifdef DEBUG |
| 46 | #define dprintf(fmt, ...) \ |
| 47 | if (slirp_debug & DBG_CALL) { fprintf(dfd, fmt, ## __VA_ARGS__); fflush(dfd); } |
| 48 | #else |
| 49 | #define dprintf(fmt, ...) |
| 50 | #endif |
| 51 | |
| 52 | static BOOTPClient *get_new_addr(struct in_addr *paddr, |
| 53 | const uint8_t *macaddr) |
| 54 | { |
| 55 | BOOTPClient *bc; |
| 56 | int i; |
| 57 | |
| 58 | for(i = 0; i < NB_ADDR; i++) { |
| 59 | bc = &bootp_clients[i]; |
| 60 | if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) |
| 61 | goto found; |
| 62 | } |
| 63 | return NULL; |
| 64 | found: |
| 65 | bc = &bootp_clients[i]; |
| 66 | bc->allocated = 1; |
| 67 | paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR)); |
| 68 | return bc; |
| 69 | } |
| 70 | |
| 71 | static BOOTPClient *request_addr(const struct in_addr *paddr, |
| 72 | const uint8_t *macaddr) |
| 73 | { |
| 74 | uint32_t req_addr = ntohl(paddr->s_addr); |
| 75 | uint32_t spec_addr = ntohl(special_addr.s_addr); |
| 76 | BOOTPClient *bc; |
| 77 | |
| 78 | if (req_addr >= (spec_addr | START_ADDR) && |
| 79 | req_addr < (spec_addr | (NB_ADDR + START_ADDR))) { |
| 80 | bc = &bootp_clients[(req_addr & 0xff) - START_ADDR]; |
| 81 | if (!bc->allocated || !memcmp(macaddr, bc->macaddr, 6)) { |
| 82 | bc->allocated = 1; |
| 83 | return bc; |
| 84 | } |
| 85 | } |
| 86 | return NULL; |
| 87 | } |
| 88 | |
| 89 | static BOOTPClient *find_addr(struct in_addr *paddr, const uint8_t *macaddr) |
| 90 | { |
| 91 | BOOTPClient *bc; |
| 92 | int i; |
| 93 | |
| 94 | for(i = 0; i < NB_ADDR; i++) { |
| 95 | if (!memcmp(macaddr, bootp_clients[i].macaddr, 6)) |
| 96 | goto found; |
| 97 | } |
| 98 | return NULL; |
| 99 | found: |
| 100 | bc = &bootp_clients[i]; |
| 101 | bc->allocated = 1; |
| 102 | paddr->s_addr = htonl(ntohl(special_addr.s_addr) | (i + START_ADDR)); |
| 103 | return bc; |
| 104 | } |
| 105 | |
| 106 | static void dhcp_decode(const struct bootp_t *bp, int *pmsg_type, |
| 107 | const struct in_addr **preq_addr) |
| 108 | { |
| 109 | const uint8_t *p, *p_end; |
| 110 | int len, tag; |
| 111 | |
| 112 | *pmsg_type = 0; |
| 113 | *preq_addr = NULL; |
| 114 | |
| 115 | p = bp->bp_vend; |
| 116 | p_end = p + DHCP_OPT_LEN; |
| 117 | if (memcmp(p, rfc1533_cookie, 4) != 0) |
| 118 | return; |
| 119 | p += 4; |
| 120 | while (p < p_end) { |
| 121 | tag = p[0]; |
| 122 | if (tag == RFC1533_PAD) { |
| 123 | p++; |
| 124 | } else if (tag == RFC1533_END) { |
| 125 | break; |
| 126 | } else { |
| 127 | p++; |
| 128 | if (p >= p_end) |
| 129 | break; |
| 130 | len = *p++; |
| 131 | dprintf("dhcp: tag=%d len=%d\n", tag, len); |
| 132 | |
| 133 | switch(tag) { |
| 134 | case RFC2132_MSG_TYPE: |
| 135 | if (len >= 1) |
| 136 | *pmsg_type = p[0]; |
| 137 | break; |
| 138 | case RFC2132_REQ_ADDR: |
| 139 | if (len >= 4) |
| 140 | *preq_addr = (struct in_addr *)p; |
| 141 | break; |
| 142 | default: |
| 143 | break; |
| 144 | } |
| 145 | p += len; |
| 146 | } |
| 147 | } |
| 148 | if (*pmsg_type == DHCPREQUEST && !*preq_addr && bp->bp_ciaddr.s_addr) { |
| 149 | *preq_addr = &bp->bp_ciaddr; |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | static void bootp_reply(const struct bootp_t *bp) |
| 154 | { |
| 155 | BOOTPClient *bc = NULL; |
| 156 | struct mbuf *m; |
| 157 | struct bootp_t *rbp; |
| 158 | struct sockaddr_in saddr, daddr; |
| 159 | struct in_addr dns_addr; |
| 160 | const struct in_addr *preq_addr; |
| 161 | int dhcp_msg_type, val; |
| 162 | uint8_t *q; |
| 163 | |
| 164 | /* extract exact DHCP msg type */ |
| 165 | dhcp_decode(bp, &dhcp_msg_type, &preq_addr); |
| 166 | dprintf("bootp packet op=%d msgtype=%d", bp->bp_op, dhcp_msg_type); |
| 167 | if (preq_addr) |
| 168 | dprintf(" req_addr=%08x\n", ntohl(preq_addr->s_addr)); |
| 169 | else |
| 170 | dprintf("\n"); |
| 171 | |
| 172 | if (dhcp_msg_type == 0) |
| 173 | dhcp_msg_type = DHCPREQUEST; /* Force reply for old BOOTP clients */ |
| 174 | |
| 175 | if (dhcp_msg_type != DHCPDISCOVER && |
| 176 | dhcp_msg_type != DHCPREQUEST) |
| 177 | return; |
| 178 | /* XXX: this is a hack to get the client mac address */ |
| 179 | memcpy(client_ethaddr, bp->bp_hwaddr, 6); |
| 180 | |
| 181 | if ((m = m_get()) == NULL) |
| 182 | return; |
| 183 | m->m_data += IF_MAXLINKHDR; |
| 184 | rbp = (struct bootp_t *)m->m_data; |
| 185 | m->m_data += sizeof(struct udpiphdr); |
| 186 | memset(rbp, 0, sizeof(struct bootp_t)); |
| 187 | |
| 188 | if (dhcp_msg_type == DHCPDISCOVER) { |
| 189 | if (preq_addr) { |
| 190 | bc = request_addr(preq_addr, client_ethaddr); |
| 191 | if (bc) { |
| 192 | daddr.sin_addr = *preq_addr; |
| 193 | } |
| 194 | } |
| 195 | if (!bc) { |
| 196 | new_addr: |
| 197 | bc = get_new_addr(&daddr.sin_addr, client_ethaddr); |
| 198 | if (!bc) { |
| 199 | dprintf("no address left\n"); |
| 200 | return; |
| 201 | } |
| 202 | } |
| 203 | memcpy(bc->macaddr, client_ethaddr, 6); |
| 204 | } else if (preq_addr) { |
| 205 | bc = request_addr(preq_addr, client_ethaddr); |
| 206 | if (bc) { |
| 207 | daddr.sin_addr = *preq_addr; |
| 208 | memcpy(bc->macaddr, client_ethaddr, 6); |
| 209 | } else { |
| 210 | daddr.sin_addr.s_addr = 0; |
| 211 | } |
| 212 | } else { |
| 213 | bc = find_addr(&daddr.sin_addr, bp->bp_hwaddr); |
| 214 | if (!bc) { |
| 215 | /* if never assigned, behaves as if it was already |
| 216 | assigned (windows fix because it remembers its address) */ |
| 217 | goto new_addr; |
| 218 | } |
| 219 | } |
| 220 | |
| 221 | saddr.sin_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_ALIAS); |
| 222 | saddr.sin_port = htons(BOOTP_SERVER); |
| 223 | |
| 224 | daddr.sin_port = htons(BOOTP_CLIENT); |
| 225 | |
| 226 | rbp->bp_op = BOOTP_REPLY; |
| 227 | rbp->bp_xid = bp->bp_xid; |
| 228 | rbp->bp_htype = 1; |
| 229 | rbp->bp_hlen = 6; |
| 230 | memcpy(rbp->bp_hwaddr, bp->bp_hwaddr, 6); |
| 231 | |
| 232 | rbp->bp_yiaddr = daddr.sin_addr; /* Client IP address */ |
| 233 | rbp->bp_siaddr = saddr.sin_addr; /* Server IP address */ |
| 234 | |
| 235 | q = rbp->bp_vend; |
| 236 | memcpy(q, rfc1533_cookie, 4); |
| 237 | q += 4; |
| 238 | |
| 239 | if (bc) { |
| 240 | dprintf("%s addr=%08x\n", |
| 241 | (dhcp_msg_type == DHCPDISCOVER) ? "offered" : "ack'ed", |
| 242 | ntohl(daddr.sin_addr.s_addr)); |
| 243 | |
| 244 | if (dhcp_msg_type == DHCPDISCOVER) { |
| 245 | *q++ = RFC2132_MSG_TYPE; |
| 246 | *q++ = 1; |
| 247 | *q++ = DHCPOFFER; |
| 248 | } else /* DHCPREQUEST */ { |
| 249 | *q++ = RFC2132_MSG_TYPE; |
| 250 | *q++ = 1; |
| 251 | *q++ = DHCPACK; |
| 252 | } |
| 253 | |
| 254 | if (bootp_filename) |
| 255 | snprintf((char *)rbp->bp_file, sizeof(rbp->bp_file), "%s", |
| 256 | bootp_filename); |
| 257 | |
| 258 | *q++ = RFC2132_SRV_ID; |
| 259 | *q++ = 4; |
| 260 | memcpy(q, &saddr.sin_addr, 4); |
| 261 | q += 4; |
| 262 | |
| 263 | *q++ = RFC1533_NETMASK; |
| 264 | *q++ = 4; |
| 265 | *q++ = 0xff; |
| 266 | *q++ = 0xff; |
| 267 | *q++ = 0xff; |
| 268 | *q++ = 0x00; |
| 269 | |
| 270 | if (!slirp_restrict) { |
| 271 | *q++ = RFC1533_GATEWAY; |
| 272 | *q++ = 4; |
| 273 | memcpy(q, &saddr.sin_addr, 4); |
| 274 | q += 4; |
| 275 | |
| 276 | *q++ = RFC1533_DNS; |
| 277 | *q++ = 4; |
| 278 | dns_addr.s_addr = htonl(ntohl(special_addr.s_addr) | CTL_DNS); |
| 279 | memcpy(q, &dns_addr, 4); |
| 280 | q += 4; |
| 281 | } |
| 282 | |
| 283 | *q++ = RFC2132_LEASE_TIME; |
| 284 | *q++ = 4; |
| 285 | val = htonl(LEASE_TIME); |
| 286 | memcpy(q, &val, 4); |
| 287 | q += 4; |
| 288 | |
| 289 | if (*slirp_hostname) { |
| 290 | val = strlen(slirp_hostname); |
| 291 | *q++ = RFC1533_HOSTNAME; |
| 292 | *q++ = val; |
| 293 | memcpy(q, slirp_hostname, val); |
| 294 | q += val; |
| 295 | } |
| 296 | } else { |
| 297 | static const char nak_msg[] = "requested address not available"; |
| 298 | |
| 299 | dprintf("nak'ed addr=%08x\n", ntohl(preq_addr->s_addr)); |
| 300 | |
| 301 | *q++ = RFC2132_MSG_TYPE; |
| 302 | *q++ = 1; |
| 303 | *q++ = DHCPNAK; |
| 304 | |
| 305 | *q++ = RFC2132_MESSAGE; |
| 306 | *q++ = sizeof(nak_msg) - 1; |
| 307 | memcpy(q, nak_msg, sizeof(nak_msg) - 1); |
| 308 | q += sizeof(nak_msg) - 1; |
| 309 | } |
| 310 | *q++ = RFC1533_END; |
| 311 | |
| 312 | daddr.sin_addr.s_addr = 0xffffffffu; |
| 313 | |
| 314 | m->m_len = sizeof(struct bootp_t) - |
| 315 | sizeof(struct ip) - sizeof(struct udphdr); |
| 316 | udp_output2(NULL, m, &saddr, &daddr, IPTOS_LOWDELAY); |
| 317 | } |
| 318 | |
| 319 | void bootp_input(struct mbuf *m) |
| 320 | { |
| 321 | struct bootp_t *bp = mtod(m, struct bootp_t *); |
| 322 | |
| 323 | if (bp->bp_op == BOOTP_REQUEST) { |
| 324 | bootp_reply(bp); |
| 325 | } |
| 326 | } |